The word time is one of the bash shell reserved words. It is not a bash shell builtin. $ builtin time bash: builtin: time: not a shell builtin Bash does support the older Bourne shell keyword times as a builtin. This builtin prints out the user and system times used by the shell and its children. So where is the time reserved word used in the bash shell? It is primarily intended for printing pipeline timing statistics. From the current online bash documentation: The format for a pipeline is [time [-p]] [!] command1 [| command2 …] The output of each